Method and apparatus for control of a gas or chemical

ABSTRACT

A method and system for control of a gas or chemical. In one embodiment, the system comprises a reactor for receipt of a fluid and the gas and/or chemical for dissolving, mixing, diffusing, or infusing the gas and/or chemical into the fluid, and a controller to control the flow of the fluid and the gas and/or chemical into the reactor. In some embodiments, the system may also monitor the operation of the system in accordance with predetermined operating conditions. In at least one embodiment, the system also comprises a gas/chemical generation system for generation of the gas and/or chemical to be introduced into the reactor.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional patent application of U.S. patent application Ser.No. 11/945,943 filed Nov. 27, 2007, which is a divisional patentapplication of U.S. patent application Ser. No. 11/454,368 filed Jun.16, 2006, now issued as U.S. Pat. No. 7,320,749, which is acontinuation-in-part of U.S. patent application Ser. No. 11/053,124,filed Feb. 8, 2005, now issued as U.S. Pat. No. 7,566,397, which is anon-provisional patent application based on U.S. provisional patentapplication Ser. No. 60/543,097, filed Feb. 9, 2004, now expired.

FIELD OF THE INVENTION

This invention relates to the field of fluid treatment, and particularlyto the introduction of a gas and/or chemical to the fluid to be treated.

BACKGROUND OF THE INVENTION

Raw domestic wastewater commonly generates offensive odors, especiallyat warmer temperatures, in collection systems and primary clarifiers atthe wastewater treatment plant, combined sewer overflows, storage tanks,lagoons, and effluents in a sewage system. The reason for generation ofoffensive odors is that the demand for dissolved oxygen by the microbesin the wastewater greatly exceeds the rate that dissolved oxygen isabsorbed into the wastewater. The main odor source at a municipalwastewater treatment plant is the effluent of the primary clarifier.This is because the raw wastewater resides in the primary clarifier forover 1 to 4 hours under anaerobic conditions. Under these anaerobicconditions, the microbes reduce sulfate to sulfide which causes theoffensive odors. Thus, when the effluent spills down the 2 to 24 inchesover the effluent weirs, the hydrogen sulfide is readily stripped out ofsolution. Consequently, many municipalities cover their primaryclarifiers, pull off the foul off gas and scrub it of the offensiveodors. This solution results in high capital cost, as well as highoperating costs.

Even though it is widely recognized that oxygen deficiency in thewastewater is the root cause of the malodorous and corrosive condition,providing sufficient dissolved oxygen has not been possible, because therags and stringy material in the raw wastewater quickly plugconventional gas transfer equipment. Furthermore, the low oxygen contentin air (21%) makes it impossible to raise the dissolved oxygen above 9mg per liter in wastewater at 25° C.

Furthermore, conventional aeration systems are very efficient atstripping out the volatile offensive sulfide complements. For instance,coarse bubble aerators generate 99 ft.³ of off gas for each 1 ft.³ ofoxygen dissolved at 5% oxygen absorbed efficiency characteristic ofcoarse bubble aerators. Surface aerators have even greater strippingpotential for sulfide. Therefore, these conventional systems cannot beused to aerate raw domestic wastewater without exacerbating the odors.

In order to prevent odor and corrosion in collection and primaryclarifiers, it has been found that wastewater should be superoxygenatedfrom about 10 mg per liter to about 60 mg per liter or higher ofdissolved oxygen. There is a widespread myth that (1) it is not possibleto achieve such high dissolved oxygen concentrations in raw municipalwastewater, and (2) that if such levels were achieved, they wouldquickly effervesce out of solution from the wastewater. High purityoxygen (“HPO”) has a water saturation concentration about five timesthat of air (40 mg per liter at 25° C.). Furthermore, HPO is expensive,and economic considerations make it preferable to utilize an oxygendissolving system that is highly efficient and has low unit energyconsumption per ton of dissolved oxygen.

The only attempts to use high purity oxygen for odor and corrosionprevention in raw municipal wastewater for gravity sewers, primaryclarifiers, collection sewage overflows, tanks and lagoons have usedgaseous oxygen injection from a diffuser in the inlet piping. However,the applications of this method have resulted in only 40% oxygenabsorption. This makes the process uneconomical, and creates anexplosion hazard with such high purity oxygen in a confined space. Ithas thus been considered that only liquid alternative oxidants, such ashydrogen peroxide and nitrate salts and chlorine and ferric salts toprecipitate sulfide, can be used for odor/corrosion prevention incollection systems and primary clarifiers at the treatment plant. Thesealternative oxidants cost over ten times as much as high purity oxygen,making them a less economic alternative, but these oxidants are analternative that is used in the current absence of efficientsuperoxygenation techniques. This problem, coupled with the pluggingproblems of rags and strings, have presented such monumental problemsthat not one single installation in the United States is known toefficiently superoxygenate raw municipal wastewater prior to gravitysewers, primary clarifiers, or combined sewage overflows to a level of10 to 60 mg per liter or higher of dissolved oxygen for odor andcorrosion control.

Thus, large cities in the southern part of the United States spendconsiderable amounts for odor/corrosion control chemicals. For example,Los Angeles County spends nearly twenty (20) million dollars per year onthe chemicals alone. Orange County California spends about 2.5 milliondollars per year for odor control chemicals such as peroxide andnitrate. Some cities inject gaseous high purity oxygen into force mains,but the low efficiency of oxygen absorption considerably increases thetotal cost, as well as presents an explosion hazard, because the highpurity oxygen bubbles immediately rise out of the wastewater and thehigh purity oxygen travels along the crown of the sewer and thencollects at the first high point when the grade of the pipe becomesnegative. This gas space also increases the head on the pump movingwater through the system. Therefore, no efficient method ofsuperoxygenating raw municipal wastewater prior to gravity sewers,primary clarifiers, or combined sewer overflows is in use in the art,resulting in the use of costly chemicals to achieve acceptable results.Therefore, a high efficiency method and apparatus for superoxygenatingraw wastewater would be beneficial.

Oxygenation has long been recognized as potentially attractive inwastewater operations. However, to make an oxygenation systemeconomically competitive, there should be commensurate savings in energycosts for dissolving the oxygen to offset the costs for the HPO supply.Early oxygenation systems were not able to achieve significant energyreductions for they consumed about half the energy needed to dissolve aunit of oxygen compared to conventional aeration systems.

Municipal wastewater treatment plants themselves can generate offensiveodors—with H₂S and mercaptans being perhaps the worst offenders. Odorstudies identify the effluent weirs from the primary clarifier as themajor source of odor generation for municipal wastewater treatmentplants. The root cause for the odor lies in the long detention times ofraw wastewater and sludge in the primary clarifier in the absence ofD.O.

One prior art approach taken to mitigate such offensive odors at themunicipal wastewater treatment plan is to cover the primary clarifierweirs, where the odor is stripped from the primary effluent as itcascades over the effluent weirs, and to withdraw the gas under thecover through ductwork and a blower. This withdrawn gas then must bepassed through a caustic chlorine scrubber or biofilter where the odoris oxidized and destroyed. Treatment of the offensive gas in this manneris costly in terms of capital cost as well as the operating costs forcaustic and chlorine. Because H₂S is so corrosive the cover and ductworkmust be made of corrosion proof material.

Another common approach to mitigating the odor at a wastewater treatmentplant is to capture and treat the offensive gases so formed. However,the use of covers on the clarifier or weirs also significantly hindermaintenance. Furthermore, every pound of oxygen consumed in the primaryclarifier translates to a 1:1 corresponding reduction of oxygen demandin the aeration tank. Therefore, it is desired to provide an efficient,cost effective system for removal of odors at municipal wastewatertreatment plants and at clarifiers.

A major effort is underway in many cities to collect, store and treatcombined sewer overflows (CSO). Such systems generally involve thecollection of a relatively large volume of CSO in a short period of timeand then storing the collected CSO for a protracted period of time—aperiod of days to weeks—while it is pumped out through a municipalwastewater treatment plant during low flow periods. The very nature ofCSO is that it can be significantly polluted in the initial “flush” withBOD concentrations of 50 to over 200 mg/L.

The challenge to meet this oxygen demand for collected CSO issignificant with present aeration systems. Further, some particulardesign considerations emerge. Aeration does not economically permit D.O.increases above 2 to 4 mg/L. In one large Midwestern city, the proposedaeration system designed to keep the stored CSO aerobic consumed from2000 to 4000 kwhr/ton of O₂ dissolved under the most frequentlyoccurring storage event, Furthermore, the electrical demand charge forthe compressors to be turned on for a 30-minute interval twice per yearalone is excessive.

If a storage basin receives a CSO storm event flow containing a BOD of100 mg/L which has a deoxygenation constant, k₁, of 0.1 per day. TheD.O. uptake for the first day in this case is 21 mg/L. Because the firstday is the highest rate, it establishes the design criteria for sizingthe required oxygen transfer system. For a storage basin of 100 MG, thesystem would require approximately a 700 HP blower for coarse bubbleaeration to meet this demand. Therefore, it is desired to provide anaeration system for use with collected CSOs that does not requiresignificant capital investment to achieve appropriate levels of D.O.

Wastewater treatment lagoons commonly are utilized for treatment ofindustrial and intensive animal rearing wastewaters. However, becausethese lagoons are commonly anaerobic and generate considerable H₂S, itis not unusual to require $1,000,000 to put a cover on such lagoons andtreat the off-gas to mitigate odor generation.

Traditionally, aeration systems have been designed to satisfy activatedsludge and aerated lagoon D.O. uptake rates of 20 to 80 mg/L-hr. Thedevelopment of some of the more advanced aerobic treatment systems whichuse advanced cell immobilization techniques are capable of ten-foldincreases in biomass concentrations. Only a properly designedoxygenation system can meet the exceptionally high oxygen uptake ratesof 300 to 500 mg/L-hr inherent in these advanced aerobic processes. Itis desired to provide such an oxygenation system.

Regulations requiring that treated effluents be discharged at elevatedD.O. concentrations to their receiving waters are specified in somedischarge permits. Conventional aeration techniques can achieve this,but do so with by requiring prohibitively high unit energy consumptionand are also limited in the D.O. that can be achieved. To increase theD.O. from 0 to 7 mg/L in water at 25° C. requires approximately 2700kwhr/ton of D.O. added using standard aeration equipment. This isequivalent to over $200/ton of D.O. for electricity rates of $0.08/kwhr.It is therefore desired to provide an aeration system that can beutilized to treat effluents to regulated levels in an energy efficientmanner.

In systems where a gas and/or chemical is to be used to treat a fluid,such as in a wastewater treatment system using dissolved oxygen to treatthe wastewater, it is desirable to control the amount of fluid to betreated and the amount of gas and/or chemical to be used for suchtreatment. Generally, such systems are designed and operated assumingstatic conditions. However, in many applications, the conditions are notstatic. When treating wastewater near a gravity force main, for example,the amount of wastewater flowing through the sewer lines, and hence tobe treated, varies significantly due to numerous factors. Therefore, itis desired to provide a system and method for treatment of a fluid witha gas and/or chemical that can accommodate the dynamic conditionsassociated with the application.

It is also preferable that such a fluid treatment system provide amonitoring function to ensure that proper design operations, andperhaps, optimal design operations, are achieved, and to avoid safetyissues associated with the system. Such safety issues may include, forexample, a build up of pressure in one or more devices caused byover-introduction of a gas into the system or under-introduction of thefluid to be treated into the system. Such a system would also save moneyby cutting back on the amount of gas and/or chemical required fortreatment of the fluid.

BRIEF SUMMARY OF THE INVENTION

The present invention comprises a system and method for treating sewage.The system of the present invention is utilized to treat the main sewagestream or a side stream and results in high oxygen absorption in anenergy efficient manner. The method of the present invention involvesthe use of the system of the present invention to oxygenate either themain sewage stream or a sidestream subsequently reintroduced into themain sewage stream.

In one embodiment, the system comprises a sewage inlet comprising partof the sewage system. The inlet is positioned for receipt and flow ofsewage therethrough and has a first end and a second end. The systemalso comprises a sewage outlet which also comprises part of the sewagesystem. The outlet is positioned for flow and discharge of sewagetherethrough. Additional components of the system include a source ofhigh purity oxygen and an oxygenator. The source of high purity oxygenis operably connected to the sewage inlet between the first and secondends of the sewage inlet and is capable of introducing high purityoxygen into the sewage inlet. The oxygenator has an inlet and an outletwith an inverse conically shaped portion therebetween. The inlet of theoxygenator is operably connected to the second end of the sewage inlet,and the outlet of the oxygenator is operably connected to the first endof the sewage outlet. The inverse conically shaped portion of theoxygenator encourages downflow of oxygen gas including the sewageprovided to the oxygenator, such that sewage discharged by the sewageoutlet is oxygenated.

In another embodiment of the system of the present invention, connectorshaving apertures therethrough are connected to a main sewage line, and apump is position near the first connector to pull a portion of thesewage flowing through the main sewage line into the previouslydescribed system.

According to one embodiment of the method of the present invention, asystem according to the present invention is provided. Sewage is thenallowed to enter the sewage inlet and oxygen gas is introduced from thesource of high purity oxygen into the sewage inlet.

In another yet embodiment, the present invention comprises a system andmethod for treatment of a fluid with a gas and/or chemical, or aplurality of gases, a plurality of chemicals, or any combinationthereof. In one embodiment, the system of the present invention includesa reactor and a controller. The reactor is a container in which the gasand/or chemical is to be dissolved, mixed, diffused, or infused, andincludes a first inlet for receipt of the fluid to be treated, a secondinlet for receipt of the gas and/or chemical, and an outlet throughwhich the treated fluid leaves the reactor. The controller is operablyconnected to the first inlet, second inlet, and outlet of the reactor.The controller is capable of controlling and monitoring the amount offluid and gas and/or chemical entering the reactor, and of measuring andcontrolling the amount of gas and/or chemical present in the treatedfluid released from the reactor.

The system of the present invention may include monitoring and/orcontrolling devices for monitoring and controlling various operationalparameters for operation of the system. Measurements that may be takeninclude, but are not limited to, temperature in the reactor, pressure inthe reactor, the flow of fluid through the fluid inlet, the volume offluid in the reactor, the flow of fluid from the fluid outlet, thetemperature of fluid in the fluid outlet, the pressure of treated fluidin the fluid outlet, and the level of dissolved, mixed, diffused, orinfused gas and/or chemical in the reactor or the fluid outlet.

The controller of the system of the present invention is capable ofcollecting data from the various monitoring and/or controlling devicesconnected to the system. The controller is also capable of comparingcollected data and calculated data to desired operational ranges forsuch collected or calculated data. The controller is further operable toadjust one or more controlling devices to try to bring all operationalparameters within the respective desired range therefor. In this manner,the system of the present invention can optimize the amount of gasand/or chemical that is dissolved, mixed, diffused, or infused into thefluid for treatment of the fluid. By making the controller furtheroperable to shut down the system in the event that the adjustments areunsuccessful, the safety of operation of the system is further ensured.By including data storage media in the controller for retention ofcollected and/or calculated data, the system can be informative as toconditions occurring prior to powering down of the system, forimprovement upon the set-up of the system, and/or to allow one to learnabout the operation of the system. Such learning may result in changesin desired ranges, for example.

According to one method of treating a fluid with a gas and/or chemicalof the present invention, a system comprising a reactor and a controlleroperably connected to the reactor is provided. Then, fluid is introducedinto the first inlet of the reactor and the gas and/or chemical isintroduced in the second inlet of the reactor. The control then measuresthe amount of gas and/or chemical present in the treated fluid releasedfrom the reactor through the fluid outlet. If the measured amount of gasand/or chemical present in the treated fluid is not as desired, thecontroller then adjusts the amount of fluid entering the reactor and/orthe amount of gas and/or chemical entering the reactor.

In another method of treating a fluid with a gas and/or chemicalaccording to the present invention, various types of data may becollected or calculated from collected data by the controller fromvarious monitoring and controlling devices made a part of the system.Generally, such data relates to the operation of the system, and rangesare established and stored in controller for such data. In this manner,controller makes adjustments to the appropriate device(s) to try tobring the parameters within the desired ranges therefor. The controllermay also log the data collected and/or calculated. In the event that theadjustments do not result in the parameters falling within the desiredranges, the controller powers down the system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic view of one embodiment of the wastewatertreatment system of the present invention.

FIG. 2 shows a block diagram of one embodiment of the apparatus forgas/chemical control according to the present invention as applied to aforce or gravity main.

FIG. 3A, FIG. 3B, and FIG. 3C show schematic diagrams of the system ofFIG. 2.

FIG. 4 shows a front view of one embodiment of the controller of theapparatus of FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 8.

FIG. 5A, FIG. 5B, FIG. 5C, and FIG. 5D show digital schematics of thecontroller of the embodiment of FIG. 4.

FIG. 6 shows a block diagram of another embodiment of a force or gravitymain system according to the present invention having the apparatus forcontrol of a gas and having a gas generation subsystem.

FIG. 7 shows a flowchart of one embodiment of the method of control of agas or chemical for treatment of a fluid according to the presentinvention.

FIG. 8 shows a schematic diagram of an alternative embodiment of thesystem of FIG. 2.

Corresponding reference characters indicate corresponding partsthroughout the several views.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a process and apparatus that allowsmunicipal waste treatment facilities to inhibit corrosive and malodorouschemicals from forming in its gravity collection systems, primaryclarifiers, or combined sewage overflows in a sewage system by readilysuperoxygenating the wastewater to effective levels. In particular, thepresent invention utilizes a down flow bubble contact oxygenator, whichhas no internal edges, corners or cracks to snag rags and strings andplug the system. In one embodiment, the down flow bubble contactoxygenator, substantially similar to that disclosed in this inventor'sU.S. Pat. No. 3,643,403 that is hereby incorporated by reference, isused to pump raw municipal wastewater through it, along with gaseous O₂injection into the chamber to superoxygenate it to 10 mg per liter ofdissolved oxygen or higher. In particular, the down flow bubble contactoxygenator is utilized in gravity sewers, primary clarifiers, orcombined sewage overflows in a sewage system to superoxygenatewastewater.

According to the present invention, oxygen is completely dissolved inthe wastewater in the discharge of the down flow bubble contactoxygenator and is then piped back into the sewage system. For example,by use of the present invention with a six-foot by six-foot square sewerflowing 5 ft. deep, the wastewater can be superoxygenated to 30 mg perliter dissolved oxygen, and only lose about 3 mg per liter of dissolvedoxygen after flowing 3 miles in a gravity sewer due to gas exchange atthe surface. Since the oxygen is in the dissolved state in the dischargeof the down flow bubble contact oxygenator, there are no gaseous bubblesto come out of solution once the water is returned to the collectionsystem or pumped into the primary clarifier. Thus, any hydrogen sulfideflowing into the superoxygenated section is microbially oxidized tosulfate in about 15 to 30 minutes once the wastewater has a positivedissolved oxygen, and no further sulfide production occurs in thisthree-mile stretch because the dissolved oxygen prevents any furthersulfate reduction to hydrogen sulfide.

Wastewater in the interceptors flowing into the head works of awastewater treatment plant superoxygenated in the manner described aboveeliminate the great odor and corrosion problems experienced at mostwastewater treatment plants due to hydrogen sulfide in the incomingwastewater. Advantages are also realized in other applications of thesystem of the present invention at various locations in the sewagesystem.

The system and method of the present invention results in precluding theformation of corrosive and odorous gas at a lower cost (capitalinvestment and energy) with highly efficient oxygen absorption andhigher superoxygenated D.O. concentrations than any of the prior artsystems. There are also additional benefits to the use of thissuperoxygenating system according to the present invention. For example,each pound of dissolved oxygen added to the stream of sewage by thesystem results in 1 lb, of dissolved oxygen saved in secondarytreatment. Thus, corrosion control is achieved for no net overallincrease in dissolved oxygen as required in secondary treatment. Anothersignificant advantage of the system utilizing the down flow bubblecontact oxygenator is the high efficiency of dissolving oxygen resultsin no off gas stripping of any volatile components in the wastewater.Thus, wastewater containing high concentrations of hydrogen sulfide canbe superoxygenated without exacerbating the odor corrosion problem, bystripping it out of solution. Additionally, under the conditions createdunder the use of this system, there is no need to cover the holdingtanks because there is no hydrogen sulfide in the discharge of thistoxic wastewater.

Use of a down flow bubble contact aeration apparatus to superoxygenatewastewater in a sewage system, superoxygenates the water to a levelwhich precludes the formation of malodorous and corrosive gases andchemicals. In particular, the use of a down flow bubble contactoxygenator allows superoxygenation of wastewater to an extent notpossible under the prior art, greatly reducing stripping of gases andsimilarly resisting clogging by rags and string endemic to rawwastewater.

Referring now to FIG. 1, there is shown a schematic view of oneembodiment of the wastewater treatment system of the present invention.As shown, main sewage line 12 is disposed below ground. System 10 may bedisposed above or below main sewage line 12. In the embodiment of FIG.1, system 10 is above platform 13 as would be case in use with a primaryclarifier, for example. If system 10 were used with a gravity sewer,system 10 intake and discharge would be below main sewage line 12. Firstand second sewer connections 14 and 16, respectively, each comprise anaperture and are made to permit sewage flow to and from system 10. Firstvalve 18 is disposed at first sewer connection 14, and second valve 20is disposed at second sewer connection 16. First and second valves 18and 20 are accessible through first and second manhole covers 19 and 21,respectively, on platform 13.

Both first valve 18 and second valve 20 are movable between an openposition and a closed position. When first valve 18 is in the closedposition, all sewage entering first sewer connection 14 is caused toflow through main sewage line 12. When first valve 18 is in the openposition, a portion of sewage entering first sewer connection 14 ispermitted to flow through system inlet 22. When second valve 20 is inthe closed position, any sewage residing in system outlet 24 is notpermitted to enter into main sewage line 12. When second valve 20 is inthe open position, any sewage residing in system outlet 24 is permittedto enter into sewage line 12.

In this embodiment, system 10 includes system inlet 22, pump 26, liquidoxygen tank 28, evaporator 30, oxygenator 32, system outlet 24, liquidoxygen connector 36, oxygen gas connector 38, and oxygenator inlet 34.System inlet is connected at its first end to first valve 18, and at itssecond end to pump 26. Pump 26 is operable to “pull” sewage from systeminlet 22 into oxygenator inlet 34. Liquid oxygen tank 28 houses liquidoxygen and evaporator 30 converts liquid oxygen into oxygen gas. Liquidoxygen connector 36 is connected at its first end to liquid oxygen tank28 and at is second end to evaporator 30, Oxygen gas connector 38 isconnected at its first end to evaporator 30 and at its second end tooxygen inlet 33 along oxygenator inlet 34. Oxygenator inlet 34 isconnected at its first end to pump 26 and at its second end atoxygenator 32.

In this embodiment, oxygenator 32 is of the shape disclosed in U.S. Pat.No. 3,643,403. However, unlike the embodiments illustrated in U.S. Pat.No. 3,643,403, oxygen is not directly inserted within the interior ofoxygenator 32. Instead, as explained herein, according to the presentinvention, oxygen is injected through oxygen inlet 33 into oxygenatorinlet 34 and then into oxygenator 32. However, like the embodimentsillustrated in U.S. Pat. No. 3,643,403, oxygenator 32 comprises a flowchamber of uniformly increasing flow area in a downward direction, i.e.,comprises conical portion 35. Oxygenator 32 may, or may not, include apower operator impeller means as disclosed in U.S. Pat. No. 3,643,403.

During operation of system 10, first and second valves 18 and 20,respectively, are placed in the open position to allow a portion ofsewage entering main sewage line 12 at first sewer connection 14 toenter system 10 and then to rejoin main sewage line 12 at second sewerconnection 16. Pump 22 is operated to “pull” the portion of sewageentering through first valve 18 through system inlet 22 and to push theportion of sewage into oxygenator inlet 34. Liquid oxygen is allowed toflow (due to the pressure in liquid oxygen tank 28) from liquid oxygentank 28 through liquid oxygen connector 36 into evaporator 30. Atevaporator 30, the liquid oxygen is converted to oxygen gas and allowedto flow (due to the pressure in liquid oxygen tank 28) through oxygengas connector 38 into oxygenator inlet 34 via oxygen inlet 33.

From the point of oxygen inlet 33 to oxygenator 32 along oxygenatorinlet 34, oxygen gas injected at oxygen inlet mixes with the sewageflowing through oxygenator inlet 34. The mixture of sewage and oxygengas enters oxygenator 32. At oxygenator 32, the bubbles of oxygen gasmixed with the sewage are drawn downward toward the bottom of oxygenator32 and system outlet 24. Thus, the mixture of sewage flowing throughsystem outlet 24 and second valve 20 into main sewage line 12 at secondsewer connection 16 is “superoxygenated”. At second sewer connection 16,the superoxygenated mixture joins the portion of sewage that was notdrawn into system 10 to oxygenate the entire sewage flowing away fromsystem 10.

It will be appreciated by those of skill in the art that the source ofoxygen gas inserted into oxygenator input 34 need not be from liquidoxygen. Instead, oxygen gas itself may be used and be within the scopeof the invention. For example, the combination of liquid oxygen tank 27,liquid oxygen connector 36, evaporator 30, and oxygen gas connector 38may be replaced with a tank of oxygen gas and a connector going from thetank of oxygen gas and oxygen inlet 33.

It will also be appreciated that the system of the present invention maybe useful in a variety of applications in a sewage system. While theembodiment of FIG. 1 illustrated an embodiment of the system used with agravity main, the system may also be used with wastewater treatmentplants, clarifiers, and combined sewer overflows prior to discharge intoreceiving waters, such as rivers.

It will be further appreciated that the system of the present inventionmay be used in the main sewage stream. An alternate embodiment of thepresent invention introduces the oxygen directly into the main streamrather than a sidestream as illustrated in FIG. 1.

The present invention provides a relatively simple technology to resultin efficient dissolution of HPO into raw sewage. The performance of theoxygenation system is, of course, related to the pressure in thesuperoxygenation transfer vessel, which in FIG. 1 comprises oxygenator32. For example, a backpressure of 15 psig would permit 100% O₂absorption in the oxygenation system while producing a discharge D.O. ofapproximately 50 mg/L. The corresponding maximum discharge D.O. for abackpressure of 45 psig would be 150 mg/L. For example, a 6 ft×6 ftsewer flowing 5 ft deep at 3 ft/sec has a reaeration rate (k₂) of about10/day. Therefore, if the D.O. is raised to 30 mg/L, it can be 86%retained over 3 miles and the head space oxygen content will only riseto a maximum of 22.5% O₂.

Superoxygenation by use of the present invention with primary clarifierinfluents provides a major advance in odor mitigation technology. Themethod of prevention of H₂S formation by use of the system of thepresent invention is a much more comprehensive solution to municipal andindustrial wastewater treatment plant odors than is gas scrubbing of theH₂S after it is formed or collection of the gas after it is formed.

With regard to combined sewer overflows, oxygenation by use of thepresent invention is considerably more cost effective than prior artaeration systems. In addition, there are some noteworthy designobjectives which can only be achieved with oxygenation by the presentinvention. Liquid oxygen stored on-site can be utilized to meet theexceptionally high initial oxygen demand of a storm event. Oxygenationby the present invention makes it possible to increase the D.O. in theincoming flows to over 50 mg/L. Since the rate of exchange of adissolved gas at the interface (k₂) of a storage basin is related to thevelocity of the water and wind and inversely proportional to the depth,very little of the superoxygenated D.O. is lost in a stagnant storagebasin containing over 10 ft of water. Thus, the super oxygenated D.O.can be kept in solution until it is consumed by the microbiota.

A design was prepared using the present invention for a large Midwesterncity which routed the peak CSO flow through the oxygenator of thepresent invention. This design raised the D.O. in the CSO to 40 mg/L asit entered the storage basin. The raising of the D.O. forestalls H₂Sgeneration by providing sufficient D.O. to meet the microbial demand forover 2 days without the need for further oxygen supplementation.

If, for some reason, the D.O. becomes depleted from a CSO storage basinwith conventional aeration systems, such as may occur by waiting toolong to turn on the aeration system, H₂S accumulates. The accumulatedH₂S is generally stripped from the water into the air by conventionalaeration systems. However, with use of the system of the presentinvention, the negligible off-gas stripping potential reduces noxiousgas stripping accordingly and eliminates the problem of oxygen transferinto septic wastewater.

As previously stated herein wastewater treatment lagoons commonly areutilized for treatment of industrial and intensive animal rearingwastewaters, but because these lagoons are commonly anaerobic andgenerate considerable H₂S, it is not unusual to require $1,000,000 toput a cover on such lagoons and treat the off-gas to mitigate odorgeneration. In contrast a properly designed oxygenation system accordingto the present invention can withdraw a sidestream of the supernatantoverlying the anaerobic sludge deposits, add 50 to 100 mg/L of D.O., andreturn it to the supernatant without disturbing the sludge layer. Usingsuch improved technology it is possible to maintain greater than 10 mg/Lof D.O. in the entire supernatant layer, with minimal loss of oxygen tothe atmosphere because the aeration rate of stagnant lagoon surfaces isrelatively low. Such elevated D.O. concentrations can successfullyprevent H₂S formation in the supernatant and also effectively oxidizethe low rates of H₂S evolution from the sludge layer.

Traditionally, prior art aeration systems have been designed to satisfyaerated lagoon D.O. uptake rates of 20 to 80 mg/L-hr. The development ofsome of the more advanced aerobic treatment systems which use advancedcell immobilization techniques are capable of ten-fold increases inbiomass concentrations. Only a properly designed oxygenation system,such as the system of the present invention, can meet the exceptionallyhigh oxygen uptake rates of 300 to 500 mg/L-hr inherent in theseadvanced aerobic processes.

While some prior art systems treat sewage at various points in thesewage system, such prior art systems are not as efficient and effectiveas the present invention. The present invention is very efficient asover 90% of oxygen gas is absorbed into the sewage stream and very highconcentrations of dissolved oxygen are achieved in the sewage discharge.Other advantages of the present invention include: (a) minimization ofthe stripping of dissolved nitrogen from the sewage when using HPO; and(b) superoxygenation of a side stream initially rather than attemptingto aerate the whole wastewater stream. Sometimes 50 to 100 mg/Lsupersaturation is required to accommodate high accumulative oxygenconsumption. Highly superoxygenated side streams incorporated into theHPO treatment design of the present invention proportionately reduce thefootprint of oxygen transfer systems as well as allow one time high D.O.additions allowing greater zones of influence in a gravity sewer. Forsatisfactory prevention of H₂S only a few mg/L of D.O. in excess of theamount consumed in transit need be maintained. This is especially suitedto odor/corrosion issues in gravity sewers, primary clarifiers, andcombined sewage overflows. For instance, a gravity main superoxygenatorcan be pressurized to about 40-ft by a pump to superoxygenate the rawsewage to about 70 mg/L D.O. easily and effectively while still keepingthe D.O. in solution.

The present invention is also operable to achieve four importantcharacteristics for high oxic conditions in wastewater and storm waterconveyance systems. These characteristics include: (a) at least 85% (forexample, 90%) efficient oxygen absorption; (b) less than 400 kwhr/tonD.O. low unit energy consumption, and at least less than 1,000 kwhr ofenergy consumption per ton of D.O.; (c) at least 10 mg/L D.O. levels ofsuperoxygenation (for example, 50 to 100 mg/L D.O. superoxygenation ofthe sidestream); and (d) effective retention of high D.O. concentrationsin solution throughout treatment.

As set forth herein, the present invention has a myriad of applicationsin treatment of sewage. These include: (a) combating H₂S formation ingravity sewers; (b) maintenance of aerobic conditions throughout theprimary clarifier for odor control; (c) maintenance of aerobicconditions in combined sewer overflow (CSO) storage tunnels and basins;and (d) achieving D.O. uptake rates of greater than 300 mg/L-hr inadvanced aerobic processes with mixed liquor suspended solids (MLVSS)concentrations exceeding 20,000 mg/L volatile suspended solids (VSS).

Referring now to FIG. 2, there is shown a block diagram of oneembodiment of the apparatus for gas/chemical control according to thepresent invention as applied to a force or gravity main. System 40 ofFIG. 2 comprises gas/chemical reactor 42, controller 44, gas/chemicalsupply 46, and fluid line 48. System 40 also comprises first valve 50,second valve 52, pump 54, first monitoring device 56, second monitoringdevice 57, and third monitoring device 58.

First valve 50 is a variable position valve operable to divert some orall of the fluid in fluid line 48 into reactor 42. In the closedposition of first valve 50, fluid flows in fluid line 48 withoutdiversion into reactor 42, and in the completely open position of firstvalve 50, fluid is diverted into reactor 42 at a level that can beaccommodated by fluid inlet 66. Because, in this embodiment, reactor 42is positioned above fluid line 48, such diversion of fluid into reactor42 also requires operation of pump 54 to move fluid from fluid line 48into reactor 42. First valve 50 can be opened at various degrees betweenthe closed position and the completely open position to control theamount of fluid diverted into reactor 42. Second valve 52 is a variableposition valve operable to allow fluid flowing from reactor 42 intofluid line 48. In the closed position of second valve 52, fluid flowsonly within fluid line 48 and no fluid is allowed to enter fluid line 48from reactor 42. In the completely open position of second valve 52,fluid is allowed to enter fluid line 48 from reactor 42 by the forces ofgravity coupled with the operation of pump 54 which pulls fluid fromfluid line 48 and pushes fluid through fluid inlet 66 into reactor 42and into fluid outlet 68. Second valve 52 can be opened at variousdegrees between the open position and the completely closed position tocontrol the amount of treated fluid from reactor 42 that enters fluidline 48. Such control of second valve 52 also results in control of theamount of time fluid remains in reactor 42, thereby effecting the amountof gas and/or chemical absorbed into the fluid in reactor 42.

The application shown in FIG. 2 is that of a force or gravity main forsewage treatment. In this application, the fluid flowing through fluidline 48 comprises sewage. When first valve 50 and second valve 52 are intheir closed positions, no fluid is permitted to flow into reactor 42.Instead, all fluid flows through fluid line 48 so that the fluidcontained in fluid line 48, the sewage in this example, is untreated.When first and second valves 50 and 52, respectively, are in their openpositions and pump 54 is activated, some or all of the fluid in fluidline 48, the sewage in this example, is pulled into reactor 42 where thepulled fluid is treated and then allowed to reenter fluid line 48 atsecond valve 52.

Gas/chemical supply 46 contains the gas and/or chemical to be used totreat the fluid contained in fluid line 48. Reactor 42 dissolves,infuses, diffuses, or mixes such gas and/or chemical into the fluid bymeans well known in the art. In the example of application in force orgravity main, gas/chemical supply 46 contains oxygen and reactor 42comprises a device capable of dissolving the oxygen into the sewagepulled into reactor 42. In one embodiment, reactor 42 comprises anoxygenator of the shape disclosed in U.S. Pat. No. 3,643,403 andcomprises a flow chamber of uniformly increasing flow area in a downwarddirection, i.e., comprises a conical portion, such as conical portion 35of FIG. 1 (see also FIG. 3B). Reactor 42 may or may not include a poweroperated impeller means as disclosed in U.S. Pat. No. 3,643,403.

Controller 44 comprises a means for monitoring and controlling variousaspects of the fluid and the gas and/or chemical as is explained ingreater detail herein. In this embodiment, controller 44 is in fluidconnection with gas/chemical supply 46 and reactor 42, and is inelectrical connection with gas/chemical supply 46, reactor 42, firstvalve 50, second valve 52, pump 54, first monitoring device 56, secondmonitoring device 57, and third monitoring device 58. Specifically, withregard to the fluid connections, controller 44 is in fluid connectionwith gas/chemical supply 46 via gas/chemical supply line 60. Controller44 is in fluid connection with reactor 42 by gas/chemical inlet 64.Reactor 42 is in fluid connection with first valve 50 via fluid inlet 66and is in fluid connection with second valve 52 via fluid outlet 68.

With regard to the electrical connections of controller 44 to otherdevices in system 40, controller 44 can control the flow of gas and/orchemical from gas/chemical supply 46 by electrical control over firstelectrical line 62. Controller 44 can control the flow of gas/chemicalinto reactor 42 and monitor certain parameters of diffusing device 42over second and third electrical lines 70 and 72, respectively. Examplesof parameters of diffusing device 42 that can be monitored by controller44 include the temperature, pressure, and chemical composition of thecontents held in diffusing device 42.

In this embodiment, controller 44 controls the operation of and collectsinformation from pump 54 over fourth electrical line 74 and fifthelectrical line 76, controls the operation of and collects informationfrom first valve 50 over sixth electrical line 78 and seventh electricalline 80, controls the operation of and collects information from secondvalve 52 over eighth electrical line 82 and ninth electrical line 83,controls the operation of and collects information from first monitoringdevice 56 over tenth electrical line 84 and eleventh electrical line 86,controls the operation of and collection of information from secondmonitoring device 57 over seventeenth electrical line 92 and eighteenthelectrical line 93, and controls the operation of and collection ofinformation from third monitoring device over twelfth electrical line 88and thirteenth electrical line 90. The types of information thatcontroller can collect or monitor from pump 54, first valve 50, andsecond valve 52 depends upon the electronic capability of pump 54, firstvalve 50, and second valve 52, and may include current status, notice offailure, etc., as is well known in the art. In this embodiment, firstmonitoring device 56 measures data regarding the flow in fluid line 48(also referred to for this embodiment as the force main flow), andsecond monitoring device 57 measures data regarding the flow of fluid influid inlet 66 (also referred to for this embodiment as the side streamflow). In this embodiment, third monitoring device 58 measures dataabout the temperature, pressure, and level of dissolved gas and/orchemical in fluid outlet 68.

It will be appreciated by those of skill in the art that each of first,second, and third monitoring devices 56, 57, and 58, respectively, maybe representative of more than one device. For example, third monitoringdevice 58 may be replaced with a pressure sensor, temperature sensor,and a meter capable of measuring the level of dissolved gas and/orchemical. It will be further appreciated that other monitoring devicesmay be made a part of system 40. Such additional monitoring devices maymeasure other operational parameters, including but not limited to thetemperature and pressure within reactor 42, for example.

The use of two electrical lines for connection of controller 44 tovarious devices in system 40 is merely illustrative of a bidirectionalelectrical connection between controller 44 and the respective device.It will be appreciated by those of skill in the art that various typesof electrical connections that comprise one or more electrical lines oreven wireless connections may be used to achieve such bidirectionalcommunication between controller 44 and the various devices. Suchalternatives are contemplated to be within the scope of the invention.It will also be appreciated by those of skill in that art thatbidirectional electrical communication is not required with each device,but is beneficial to allow controller 44 to control the device and tocollect data either measured by the device or indicative of the statusof the device. For example, while it may only be necessary to controlthe operation of pump 54 with controller 44, it is advantageous forcontroller 44 to collect information about the status of pump 54 madeavailable by the electronics of pump 54. As another example, while itmay only be necessary to collect the data measured by first monitoringdevice 56, it is advantageous for controller 44 to be able to send asignal to first monitoring device 56 to activate first monitoring device56 and to ensure that first monitoring device 56 is operating properly.

FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 8 show schematic diagrams of thesystem of FIG. 2. Specifically, FIG. 3A shows a schematic diagram ofthat portion of system 40 including fluid line 48, fluid inlet 66, firstmonitoring device 56, second monitoring device 57, and first valve 50.FIG. 3B shows a schematic diagram of that portion of system 40 includingthe continuation of fluid line 48, fluid inlet 66, fluid outlet 68,gas/chemical inlet 64, reactor 42, third monitoring device 58, andsecond valve 52. In this embodiment, reactor 42 further comprises fluidport 100 for receipt of fluid from fluid inlet 66 into diffusing device42 and gas/chemical port 102 for receipt of gas/chemical fromgas/chemical inlet 64 into reactor 42. FIG. 3C shows a schematic diagramof that portion of system 40 including fluid line 48, gas/chemical inlet64, gas/chemical supply line 60, controller 44, and gas/chemical supply46. FIG. 8 shows an alternate embodiment of that portion of system 40wherein a third monitoring device 240 is positioned within the reactor42. In this embodiment, the third monitoring device 240 is equivalent tothe third monitoring device 58 of FIG. 3B. One embodiment of theelectronics used to achieve the electrical communication of the devicesshown in FIG. 2 and in FIGS. 3A, 3B, 3C, and FIG. 8 are shown in greaterdetail in association with FIG. 5A, FIG. 5B, FIG. 5C, and FIG. 5Dhereof.

Referring now to FIG. 4, there is shown a front view of one embodimentof the controller of the apparatus of FIG. 3A, FIG. 3B, FIG. 3C, andFIG. 8. In this embodiment, controller 44 comprises first panel 110 andsecond panel 112. First panel 110 comprises an input/output device 114and an emergency stop 116. Input/output device 114 allows an operator toenter data and to see the data entered as well as information about theoperation of system 40. In one embodiment, an operator may view all thedata collected by controller 44. Emergency stop 116, when activated byan operator, stops the operation controller 44 and the various devicesof system 40 to which controller 44 is connected. Second panel 112comprises first controller valve 120 for receipt of the gas and/orchemical from gas/chemical supply line 60, second controller valve 122to control flow of gas and/or chemical from controller 44 togas/chemical line 64, and third controller valve 124 to automaticallycontrol the flow of the gas and/or chemical from gas/chemical supply 46(see FIG. 2) through gas/chemical supply line 60 to reactor 42 (see FIG.2) from gas/chemical line 64. Second panel 112 also includes manual gasand/or chemical adjustment device 118 to control the flow of gas and/orchemical from gas/chemical supply 46 to reactor 42 in the event thatthird controller valve 124, which serves as an automatic adjustmentdevice, is not operating or is operating improperly. In this embodiment,each third controller valve 124 and manual adjustment device 118, andthe combination of third controller valve 124 and manual adjustmentdevice 118, serve as a flow meter for control of the flow of gas and/orchemical into reactor 42.

FIG. 5A, FIG. 5B, FIG. 5C, and FIG. 5D show digital schematics of thecontroller of the embodiment of FIG. 4. Collectively, FIG. 5A, FIG. 5B,FIG. 5C, and FIG. 5D show one embodiment of the electronics used forsystem 40. In this embodiment, the electronics of system 40 usesprogrammable logic controllers (“PLCs”) for connection of controller 44to various devices of system 40, for control of such devices, and forcollection of information from such devices. In this embodiment, PLCsavailable from Allen-Bradley, namely, model numbers Micrologix 12001769-L40AWA (see FIG. 5C) and Micrologix 1762-IF20F2 (see FIG. 5D), areused for this purpose. The connections of the components of controller44 and of devices external to the PLCs of controller 44 are illustratedin FIG. 5C and FIG. 5D. The mass flow controller portion of controller44 is illustrated in FIG. 5B, and the power connections of thecomponents of controller 44 are illustrated in FIG. 5A.

Referring now to FIG. 6, there is shown a block diagram of anotherembodiment of a force or gravity main system according to the presentinvention having the apparatus for control of a gas and having a gasgeneration subsystem. System 200 differs from that of system 40 of FIG.2 by the addition of gas/chemical generation system 202, generatedgas/chemical line 204, fourteenth electrical line 206, fifteenthelectrical line 208, and sixteenth electrical line 210. Gas/chemicalgeneration system 202 is a system for generation of the gas and/orchemical to be used to treat the fluid. Such systems are well known inthe art.

For example, for treatment of wastewater in the force gravity mainapplication, the gas used to treat the wastewater is oxygen. In thisembodiment, gas/chemical generation system 202 is used to generateoxygen. An example of an oxygen generation system includes the mid-sizegenerators made by Oxygen Generating Systems International of NorthTonawanda, N.Y. The oxygen generation systems of Oxygen GeneratingSystems International usually comprise an air compressor, air dryer, airreceiver tank, and oxygen generator. The air compressor compresses airand includes particulate and coalescing filters. The compressed andfilter air flows from the air compressor the air dryer where the air isdried. The dried air is then sent to an air receiver tank. The filtered,dried air from the air receiving tank is then fed into a generator wheresubstantially pure oxygen is generated from the air. The substantiallypure oxygen can then be fed into a supply tank, such as gas/chemicalsupply 46 show in FIG. 6.

Returning now to FIG. 6, gas/chemical generation system 202 is in fluidconnection with gas/chemical supply 46 via generated gas/chemical line204. In this embodiment, gas/chemical generation system 202 iselectrically connected via fourteenth and fifteenth electrical lines 206and 208 to permit controller 44 to control, monitor, and collectinformation from gas/chemical generation system. In this embodiment,another electrical line, namely, sixteenth electrical line 210, is addedbetween gas/chemical supply 46 and controller 44 to permit formonitoring and collection of information from gas/chemical supply 46. Inthis manner, system 200 is a closed loop system—having all operabledevices connected to controller 44.

As was discussed above in association with FIG. 2, the use of two linesbetween devices in FIG. 6 is illustrative of bidirectional communicationbetween the device and controller 44. It will be appreciated that it maybe desirable in FIG. 2 to include bidirectional communication betweencontroller 44 and gas/chemical supply 46, and such is contemplated to bewithin the scope of the invention.

Turning now to the operation of system 40 of FIG. 2, FIG. 7 shows aflowchart of one embodiment of the method of control of a gas orchemical for treatment of a fluid according to the present invention.The operation of system 40 begins at step 220. Steps 222, 224, 226, and228 are initialization steps that occur prior to powering on of system40 in step 230. At step 222, the volume of fluid to be treated (the flowof fluid through fluid line 48 that is to be treated) is entered intocontroller 44 as are the bounds for various parameters to be monitoredby controller 44. Entry of such data may occur manually at input/outputdevice 114 (see FIG. 4) and/or be programmed into controller 44. In oneembodiment wherein system 40 is used in a force or gravity main fortreatment of wastewater, such parameters and their bounds are:

Lower Parameter Bounds (About) Upper Bounds (About) Temperature ofcontents of 0° C. 50° C. reactor 42 as measured by a temperature sensorincluded in reactor 42 or at third monitoring device 58 Pressure ofcontents of reactor 0 psi 100 psi 42 as measured by a pressure sensorincluded in reactor 42 or at third monitoring device 58 Side stream flowat second 0 gpm 10,000 gpm monitoring device 57 Flow from gas/chemical 0scfm 50 scfm supply line 60 as measured by flow meter (118 and/or 124)Flow from gas/chemical inlet 0 scfm 50 scfm 64 as measured by a sensorplaced along gas/chemical inlet 64 Level of dissolved 0 mg/L 200 ml/Lgas/chemical (in this embodiment, dissolved oxygen) from thirdmonitoring device 58 Gas/chemical absorption 0% 98% efficiency (percentof gas/chemical metered into reactor 42 that is actually dissolved, andis calculated by dividing the level of dissolved gas/chemical by theflow rate at gas/chemical inlet 64) Force main flow measured by 0 gpm50,000 gpm first monitoring device 56

At step 224, the hydraulic retention time (“HRT”) of the fluid inreactor 42 is calculated. HRT is calculated by dividing the volumeentered in step 222 by the fluid flow rate through line 48.

The gas/chemical uptake rate is determined at step 226 based on thetemperature of the fluid in reactor 42 or as measured by thirdmonitoring device 58 (as such information is collected by controller44). In one embodiment of the example of use in a force or gravity mainfor wastewater treatment, if the temperature of the fluid measured inreactor 42 (or as measured by third monitoring device 58) is from about0° C. to about 15° C., then the oxygen uptake rate is set at about 5mg/L/hr; if the measured temperature is from above about 15° C. to about34° C., then the oxygen uptake rate is set at about 10 mg/L/hr; and ifthe measured temperature is greater than from about 34° C., then theoxygen uptake rate is set at about 15 mg/L/hr. Such rates are generallybased on prior measurements or experience, or on desired levels, and maybe determined based on a table or, for greater precision, in accordancewith an appropriate equation.

At step 228, the gas/chemical demand is calculated. The gas/chemicaldemand is calculated by multiplying the HRT by the gas/chemical uptakerate. At step 230, controller 44 activates various devices to which itis electrically connected. In one embodiment, controller 44:

(a) places first valve 50 in its second position, places second valve 52is its second position, and activates pump 54 to allow fluid to flowfrom fluid line 48 through fluid port 100 into reactor 42;(b) activates gas/chemical supply 46, sets flow meter 118 and/or 124 tothe calculated gas/chemical demand, and opens first controller valve 120and second controller valve 122 to permit the gas and/or chemical fromgas/chemical supply 46 to flow through gas/chemical supply line 60 intogas/chemical inlet 64 and through gas/chemical port 102 into reactor 42;and(c) activates first, second, and third monitoring devices 56, 57, and58, respectively, to enable controller 42 to collect data from first,second, and third monitoring devices 56, 57, and 58, respectively. Atthe conclusion of step 230, system 40 is operational to treat the fluidwith the gas and/or chemical in reactor 42.

At step 230, controller 42 begins to monitor various parameters toensure proper and safe operation of system 40. At step 232, each of theparameters is compared to the upper and lower bounds established forthat parameter. Ideally, such comparison should be simultaneous, and ornear simultaneous, so that not significant time elapses in making allthe comparison necessary.

If it is determined at step 232 that all of the parameters are withinthe specified range for that parameter, controller 44 returns to step232. If, on the other hand, one or more of the parameters is out of itsspecified range, the controller proceeds to make appropriate systemadjustments in step 234. Specific adjustments for various parameters arediscussed later herein. At step 236, controller 44 looks at appropriatedata to ascertain whether the adjustment(s) made were successful, i.e.,to determine if all parameters are within the specified range for thatparameter. If all parameters are in the specified ranges, controller 44returns to step 232. If, on the other hand, all parameters are notwithin the specified ranges, controller 44 proceeds to step 238. At step238, controller 44 issues an alarm and powers off the system. Theissuance of the alarm by controller 44 may comprise a visual and/or anaudio alarm, a computer message, or any other alarming device well knownin the art. The process of powering off system 40 in step 238 includes:(a) turning off pump 54 and placing first and second valves 50 and 52,respectively, in their closed positions to prohibit the flow of fluidfrom fluid line 48 into reactor 42; (b) closing first controller valve120 and second controller valve 122 and deactivating gas/chemical supply46 to prohibit the gas and/or chemical from gas/chemical supply 46 fromflowing into reactor 42; and (c) optionally, deactivating first, second,and third monitoring devices 56, 57, and 58, respectively. At step 240,the monitoring of system 40 is illustrated to end.

With respect to steps 232, 234, 236, 238, and 240, immediately followingare some examples of the handling of parameters monitored by controller44. Pump 54 is monitored by controller 44 to ensure operation inaccordance with design operating conditions. Specifically, the sidestream flow at pump 54 is monitored by second monitoring device 57, andif it is determined at step 232 that the measured side stream flowexceed the specified bounds therefor, controller 44 adjusts pump 54 atstep 234 to try to bring the side stream flow within specifiedtolerances. If it is determined at step 236 that the side stream flow,or any other parameter, is out of tolerances, then controller 44proceeds to step 238 to issue an alarm and power down system 40.

The flow of gas and/or chemical through controller 44 is measured toensure performance in accordance with predetermined design operatingconditions. Specifically, at step 232, the flow rate at gas/chemicalsupply line 60 and/or at gas/chemical inlet 64 is compared by controller44 to the specified range(s) therefor. If it is determined at step 232that the flow exceeds the specified range, at step 234, controller 44adjusts flow meter 118 and/or 124 to attempt to bring the flow of gasand/or chemical within the specified range. If it is determined at step236 that the flow of gas and/or chemical is still outside tolerances, orif any other parameter is outside of that parameter's tolerances, then,at step 238, controller 44 proceeds to issue an alarm and power downsystem 40.

The level of dissolved gas and/or chemical is monitored to ensureoperating performance in accordance with predetermined design operatingconditions. The level of dissolved gas and/or chemical is measured atthird monitoring device 58. If at step 232, it is determined that themeasured level of dissolved gas and/or chemical exceeds the specifiedtolerances, then controller 44 at step 234 adjusts flow meter 118 and/or124, and/or adjusts first valve 50 and/or second valve 52 (to adjust theamount of time fluid is retained in reactor 42) to try to bring thelevel of dissolved gas and/or chemical into specified tolerances. If itis determined at step 239 that the level of gas and/or chemical is stilloutside tolerances, or if any other parameter is outside of thatparameter's specified range, then controller 44, at step 238, proceedsto issue and alarm and power down system 40.

With regard to the measurement of dissolved gas and/or chemical, it willbe appreciated that the measurement and adjustments made in response tothe measurement provides a dynamic feedback parameter for control of thegas and/or chemical injection into reactor 42, without regard to whetherthe level of dissolved gas and/or chemical exceeds the specifiedtolerances. For example, it is generally desired to maintain a preferredlevel of dissolved gas and/or chemical in reactor 42, and controller 44can be used to increase or decrease the rate of injection of gas and/orchemical into reactor 42 to maintain such a desired level.

The gas/chemical dissolution rate is the amount of gas and/or chemicaldissolved by reactor 42. The gas/chemical dissolution rate is calculatedand monitored by controller 44 to ensure operating performance inaccordance with predetermined design operating conditions. Thecalculation of the gas/chemical dissolution rate is made using standardgas transfer equations, and involves the multiplication of the measureddissolved gas/chemical value, gas transfer coefficient, and side streamflow rate to show the amount of gas and/or chemical dissolved in aspecified time period. If the gas/chemical dissolution rate isdetermined in step 232 to be out of the specified tolerances, controller44 may, in step 234, adjust the feedrate of the gas and/or chemical withflow meter 118 and/or 124, and/or adjust first valve 50 and/or secondvalve 52 (to control the retention time in reactor 42) to resolve theissue. If it is determined at step 236 that the gas/chemical dissolutionrate is still out of tolerances, or any other parameter is out of itsspecified tolerances, controller 44 proceeds to step 238 to issue andalarm and to power off system 40.

The gas/chemical absorption efficiency is the percent of gas and/orchemical metered into reactor 40 that is dissolved into the fluid inreactor 42, and therefore is measured by examining the level of diffusedgas/chemical in reactor and measuring the gas and/or chemical flow rateat flow meter 118 and/or 124. In the event it is determined at step 232that the absorption efficient is out of specified tolerances, controller44, at step 234 adjusts the feedrate of the gas and/or chemical withflow meter 118 and/or 124. If it determined at step 236 that theabsorption efficiency is still out of tolerances, or any other parameteris out of its specified tolerances, controller 44 proceeds to step 238to issue an alarm and power down system 40.

Pressure and temperature within reactor 42 or as measured by thirdmonitoring device 58 are monitored to ensure operating performance inaccordance with predetermined design operating conditions. If it isdetermined by controller 44 at step 232 that either pressure ortemperature are out of the desired respective tolerances, controller 44,at step 234, adjusts the pressure in reactor 42 by adjusting first valve50 and/or second valve 52. If controller 44 determines at step 236 thatpressure or temperature, or any other parameter, is outside of therespective tolerances, then controller 44 proceeds to step 238 to issueand alarm and to power down system 40.

The measurement of side stream flow by second monitoring device 57 isalso desired for reasons other than maintaining the appropriateintroduction of gas and/or chemical into reactor 42. If controller 44determines that there is no or substantially no flow in the side streamby measurement with second monitoring device 57, controller 44 mayproceed to power down system 40 or to restrict the introduction of gasand/or chemical into system 40 to avoid the accumulation of gas and/orchemical either in reactor 42 or into fluid line 48 where the gas and/orchemical could pose a safety hazard. In the embodiment of system 40applied in a force or gravity main, such low side stream condition couldalso be accommodated by recycling the reactor 42 effluent back into theinfluent by leaving first valve 50 is its second position, and placingsecond valve 52 in a closed position.

With regard to the operation of system 200 of FIG. 6, the same processmay be used as is used in connection with system 40 of FIG. 2. Inaddition, controller 44 may control the generation of gas and/orchemical by gas/chemical generation system 202, and to ensure thatenough gas and/or chemical is present in gas/chemical supply 46.

While the example discussed above in association with FIG. 2, FIG. 3A,FIG. 3B, FIG. 3C, FIG. 4, FIG. 5A, FIG. 5B, FIG. 5C, FIG. 5D, FIG. 6,and FIG. 7 is a force or gravity main water treatment application, itwill be appreciated by those of skill in the art that other applicationsfor the dissolution of a gas and/or chemical into a fluid for treatmentof the fluid are contemplated to be within the scope of the invention.For example, the apparatus and method of the present invention may beused in systems to control hydrogen gas for saturating unsaturated fatsand oils, for hydrogenation of coal conversion products, for theintroduction of ozone for water treatment, for introduction of methanegas for methanotrophic bacteria bioremediating trichloroethylenecontamination in ground water, for stripping dissolved nitrogen fromwater used in aquaculture by injecting oxygen gas, for treating water orwastewater with the oxygen contained in air, and for treating wastewaterwith oxygen together with a chemical such as chlorine, peroxide, ornitrate.

It will also be appreciated that the prior art systems for thedissolution of a gas and/or chemical into a fluid for treatment of thefluid do not completely dissolve, mix, diffuse, or infuse the gas and/orchemical before it is discharged into the fluid line or receiving tank.The present invention completely dissolves, mixes, diffuses, or infusesthe gas and/or chemical prior to discharge, and provides control overthe level of gas and/or chemical dissolved, mixed, diffused, or infused.In addition, the present invention incorporates dynamic feedback controlfor control of gas and/or chemical injection to match the demand for thegas and/or chemical into the system for the desired results.

Further, because controller 44 is in communication with various devicesfor the collection of data from such devices and for the control of suchdevices, controller 44 may retain in data storage media the datacollected, data representative of status of the devices as controlled bycontroller 44 (open, closed, etc.), the parametric data, the establishedtolerances for the parameters, and/or the calculated data. The retentionof such data is beneficial for several reasons. Examination of the databy means well known in the art may be informative as to conditionsoccurring prior to powering down of the system, to improve upon theset-up of the system, and/or to learn about the operation of the system.Such learning may result in changes in tolerances, for example.

It will be further appreciated that the system and method of the presentinvention accommodate changes in demand for the supply of the gas and/orchemical to the reactor as the system's operating parameters change. Theability to accommodate such changes assists to ensure that the system isoperating optimally under the changing circumstances. In application forwastewater treatment, the system assists to avoid the odor and corrosioncaused by insufficient levels of dissolved oxygen, and for aeration ofwater systems, the system assists in avoidance of the aquatic lifedisruption.

It will be yet further appreciated that the system of the presentinvention is comprised of commercially available and reasonably pricedcomponents, so as to result in a system that is reasonable in capitalcosts and in the costs associated with maintenance and repair. Forexample, controller 44 as illustrated herein is comprised of PLCs, anoperator interface terminal, and alarm notification instrumentationavailable from more than one manufacturing source. Generally, controller44 comprises at least one processor, such as the PLCs,microprocessor(s), or other combinations of hardware and/or softwarewell known in the art. Controller 44 may also comprise data storagemedia (memory, RAM, hard disk, memory stick, or other devices well knownin the art) for the storage of the entered volume, the parameters, andthe tolerances for the parameters, and for retention of the operationaldata collected during operation of the system according to the presentinvention.

It will still further appreciated that, while various specificelectronics are illustrated in FIG. 3A, FIG. 3B, FIG. 3C, FIG. 4, FIG.5A, FIG. 5B, FIG. 5C, and FIG. 5D, various alternatives to suchelectronics that are well known in the art are contemplated to be withinthe scope of the invention. For example, in lieu, of or in concert withthe use of PLCs, various combinations of hardware and/or software mayserve the same function as set forth herein.

It will be yet further appreciated that the addition of a gas/chemicalgeneration system, such as is illustrated in association with FIG. 6,results in a self-contained system requiring only that the initialmaterial be made available to the generation system and that power beprovided to the system. In the case of oxygen generation, no initialmaterial is required to be provided as oxygen is generated from air.Thus, regardless of the gas and/or chemical to be introduced, theaddition of the generation system reduces the costs associated withoperation and limits the number of personnel required for operation ofthe system.

It will also be appreciated that it is possible to eliminate therequirement of the gas/chemical supply in the system of the presentinvention. Such elimination is conceivable if a readily available supplyof the gas and/or chemical used to treat the fluid is available withoutstorage. For example, when the system includes the generation system, ifthe generation system is able to produce the gas and/or chemical atrates equal to or greater than the demand for operation of the system,the gas/chemical supply would not be needed in such a system.

It will be further appreciated that variations may be made to theprocess of adjustments made for a parameter that is out of the specifiedtolerances and be within the scope of the invention. The examples givenherein are based on a single measurement of parameters made after theadjustment has been made. This is a very tight system—one that canquickly result in the system being powered down. One may lengthen thetime period the controller uses between the subsequent measurements tobe more forgiving. Alternatively, a series of measurements may be madebefore the system is powered down. By making a series of measurements,the controller can ascertain whether the adjustment(s) made are in theprocess of resolving the out-of-bounds parameter, and, if such progressis determined to be in process, the controller may continue to makeadditional adjustment(s) or wait a longer period of time to see if thesystem and all parameters returns to a desired and/or safe operation.Various of these techniques, as well as others well known in the art,may be used for all parameters or for different parameters. For example,if pressure in the reactor exceeds a safe threshold, the system can beimmediately powered down, but if other less critical parameters, such asa level of dissolved gas and/or chemical is slightly below the lowerthreshold, the controller could be “more patient” and allow for either agreater amount of time and/or make several measurements beforedetermining it is necessary to power down the system.

As used in the claims, the term “treatment additive” refers to the gasand/or chemical to be added to the fluid. A treatment additive comprisesat least one of a gas or chemical, and may comprise a combination of agas and a chemical, a gas introduced to the reactor at one port and achemical introduced to the reactor at another port, or any number ofgases and/or chemicals introduced together and/or separately to thereactor. By use of this term, measurement related to the treatmentadditive may comprise separate measurements of each gas and/or chemical,and/or measurements of the combination of all gases and chemicalsintroduced into the reactor.

In view of the many possible embodiments to which the principles ofthese invention may be applied, it should be recognized that thedetailed embodiments are illustrative only and should not be taken aslimiting the scope of the invention. Rather, the invention comprises allsuch embodiments as may come within the scope and spirit of theinvention and equivalents thereto.

1. A system for treatment of a fluid with a treatment additive, thesystem comprising: a reactor having a first inlet and an outlet; a fluidline having first and second valves disposed therein; a fluid inletconnected to the first valve and to the first inlet of the reactor, andwherein the first valve controls the flow of fluid into the first inletof the reactor; a treatment additive inlet operatively connected to thereactor and to a supply of a treatment additive; a treatment additivevalve within the treatment additive inlet capable of controlling theflow of treatment additive into the reactor; a fluid outlet connected tothe outlet of the reactor and to the second valve, and wherein thesecond valve controls the flow of treated fluid from the outlet of thereactor; and a controller operably connected to the treatment additivevalve, the controller capable of controlling the flow of treatmentadditive through the treatment additive valve into the reactor, and thecontroller further operable to measure the amount of treatment additivepresent in the treated fluid exiting the reactor.
 2. The system of claim1, wherein the treatment additive inlet is operably connected to thefluid inlet.
 3. The system of claim 1, wherein the reactor furthercomprises a second inlet operably coupled to the treatment additiveinlet.
 4. The system of claim 1, wherein the controller is operablyconnected to the first valve and the second valve, the controllercapable of controlling the flow of fluid entering the reactor and theamount of treated fluid exiting the reactor through the outlet.
 5. Thesystem of claim 1, further comprising a treatment additive generatoroperably connected to the supply of treatment additive, the treatmentadditive generator capable of generating the treatment additive from atleast one ingredient.
 6. A method for treating a fluid with a treatmentadditive, the method comprising the steps of: providing a systemincluding a reactor having a first inlet capable of receipt of an amountof the fluid and an outlet capable of release of fluid therefrom, asupply of a treatment additive operably connected to the reactor, and acontroller operably connected to the first inlet and the outlet of thereactor; introducing, under control of the controller, the fluid intothe first inlet of the reactor and the treatment additive into thereactor; measuring, with the controller, the amount of treatmentadditive present in the treated fluid released from the reactor; andadjusting, under control of the controller, the amount of treatmentadditive introduced into the reactor in response to the amount oftreatment additive measured as present in the treatment fluid.
 7. Themethod of claim 6, further comprises the step of controlling, with thecontroller, the flow of fluid entering the reactor and the amount oftreated fluid exiting the reactor through the outlet.
 8. The method ofclaim 6, further comprising the step of: adjusting, under the control ofthe controller, the amount of fluid introduced into the first inlet ofthe reactor in response to the amount of treatment additive measured aspresent in the treated fluid.
 9. The method of claim 6, furthercomprising the step of: adjusting, under control of the controller, theamount of fluid introduced into the first inlet of the reactor and theamount of treatment additive introduced into the at least one secondinlet of the reactor, both in response to the amount of treatmentadditive measured as present in the treated fluid.
 10. The method ofclaim 6, further comprising the step of: establishing a desired rangefor flow of fluid into the reactor; measuring with the controller theamount of fluid entering the reactor; comparing with the controller themeasured amount of fluid entering into the reactor to the desired range;and if the controller determines in the step of comparing the measuredamount that the measured amount is outside the desired range, thecontroller adjusts the introduction of fluid into the reactor or adjuststhe introduction of treatment additive into the reactor.
 11. The methodof claim 6, wherein the system further comprises a pressure sensor formeasuring the pressure within the reactor, the pressure sensor operablyconnected to the controller, the method further comprising the step of:establishing the desired range pressure within the reactor; measuringwith the pressure sensor the pressure within the reactor; comparing withthe controller the measured pressure to the desired range; and if thecontroller determines in the step of comparing the measured pressurethat the measured pressure is outside the desired range, the controllerthen adjusts the introduction of fluid into the reactor, adjusts theintroduction of treatment additive into the reactor, and/or adjusts theflow of treated fluid through the outlet.
 12. The method of claim 6,wherein the system further comprises a fluid inlet operably connected tothe first outlet, a pump located along the fluid inlet before the firstinlet of the reactor for control of the flow of the fluid into thereactor, and a monitoring device located along the fluid inlet beforethe pump, the monitoring device capable of measuring the flow of fluidthrough the fluid inlet, and the pump and monitoring device operablyconnected to the controller, the method further comprising the steps of:establishing the desired range for flow of fluid through the monitoringdevice; measuring with the monitoring device the flow of fluid;comparing with the controller the measured flow of fluid to the desirerange; and if the controller determines in the comparing step that themeasured flow of fluid is outside the desired range, adjusting with thepump the flow of fluid.
 13. The method of claim 6, wherein the systemfurther comprises a monitoring device capable of measuring the level oftreatment additive in the treated fluid, the monitoring device locatedoutside the outlet of the reactor and operably connected to thecontroller, the method further comprising the steps of: establishing thedesired range for the level of treatment additive in the treated fluid;measuring with the monitoring device the level of treatment additive inthe treated fluid; comparing with the controller the measured level oftreatment additive in the treated fluid to the desired range; and if thecontroller determines that the measure level of treatment additive inthe fluid is outside the desired range, the controller adjusts theamount of fluid entering the reactor through the first inlet, the amountof treatment additive entering the reactor through the second inlet,and/or the amount treated fluid flowing from the reactor at the outlet.14. A method for treating a fluid with a treatment additive, the methodcomprising the steps of: providing a system including a reactor having afirst inlet for receipt of an amount of the fluid, at least one secondinlet for receipt of an amount of the treatment additive, and an outletfor release of an amount of treated fluid therefrom, at least one devicefor collection of data related to the operation of the system, and acontroller operably connected to the reactor at the first inlet, the atleast one second inlet, and the outlet, the controller operablyconnected to the at least one device and including means for datastorage of the data collected by the at least one device, the controllercapable of controlling the amount of fluid entering the reactor, theamount of treatment additive entering the reactor, and the amount oftreated fluid released from the reactor; operating the reactor with thecontroller; and collecting in the means for data storage of thecontroller data collected by the at least one device during operation ofthe reactor.
 15. The method of claim 14, wherein the system furthercomprises a monitoring device capable of measuring the level oftreatment additive in the treated fluid, the monitoring devicepositioned within the reactor and operably connected to the controller,the method further comprising the steps of: establishing the desiredrange for the level of treatment additive in the treated fluid;measuring with the monitoring device the level of treatment additive inthe treated fluid; comparing with the controller the measured level oftreatment additive in the treated fluid to the desired range; and if thecontroller determines that the measure level of treatment additive inthe fluid is outside the desired range, the controller adjusts theamount of fluid entering the reactor through the first inlet, the amountof treatment additive entering the reactor through the second inlet,and/or the amount treated fluid flowing from the reactor at the outlet.